The present invention relates to an armature winding, a method for manufacturing the armature winding, and a slotless motor.
A slotless motor is a motor that uses an armature that does not include a steel core thereby reducing cogging torque or torque ripple in comparison with a motor that uses an armature including a steel core. Since the mass of the armature that does not include a steel core is small, the drivability of the motor becomes satisfactory when the armature that does not include a steel core is used on the rotor side. The motor can be miniaturized if the armature that does not include a steel core is used on the stator side since the dimension for a steel core in the radial direction becomes unnecessary.
Such a slotless motor is disclosed in, for example, Japanese Laid-Open Patent Publication No. 8-322221. In the slotless motor of the publication, stripes made of copper foil extending helically are arranged on a cylinder made of plastic resin to form an armature winding. Such an armature winding may be formed by performing photo-etching and is thus easily manufactured.
However, since the stripes made of copper foil receive current in the above described armature winding, the amount of current that flows through the armature winding is limited. Thus, it becomes difficult to obtain a large motor output. Further, sufficient space for insulation must be provided between the adjacent stripes since each stripe is not covered by an insulator. Thus, the stripes cannot be densely arranged. This is also another reason why it is difficult to obtain a large motor output.